I have a service bus topic subscription model . I am in control of designing the sender component to a topic. however receiver is a remote server whose code i cannot control. Now the tricky part, is i need to somehow possibly know some stats from service bus without really having to ask the remote server to do additional work.
For eg.
1)Last message processed (it's content)
2)Last message completed succesfully - Time and content.
This is for basic troubleshooting on my word to know, that message has atleast been recieved by the receiver.
Is it possible to do this?
What does it mean "Last message processed" and "Last message completed succesfully". If you have a constant stream of messages, at what point you would determine what's a last message.
What you're asking is somewhat in violation of the pub/sub concept. The whole point of topics and subscriptions is to decouple publishers and subscribers.
This is for basic troubleshooting on my word to know, that message has atleast been recieved by the receiver.
When messages are sent to the subscription queue, they are either consumed or eventually end up in the dead-letter queue. If they are in the dead-letter queue, you'll know the reason. In case they are consumed, you will have to trust the consumer it knows what it's doing. Any time of "reply" or "acknowledgement" goes against the concept of events, where you broadcast of something that has happened and should not carry if it was received or not.
Related
If I have a service bus brokered message receiver configured. and it fails for any reason. I call on it
message.abandon();
however this means the message will be back again in the queue/subscription.
can i configure a timeout after which the same message is available in the queue for processing.
For example: if there is only one message in the queue. and it's failing, then it is not good to keep processing it every second or every minute. if i configure something, that can make sure, the failed/abandoned message only reappears after 30 mins . then it is useful.
Any suggestions?
When you abandon a message, you cannot supply a "cool off" time. The message will be available right away. It won't be dead-lettered until MaxDeliveryCount attempts have been exhausted. Once all those processing attempts have been used up, the message will go to the dead-letter queue.
If you need to postpone message processing, there are several options.
Deferring a message
You could defer a message using BrokeredMessage.DeferAsync(). The message will go back to the queue for future processing and a SequenceNumber of the message will be returned. The caveat with this approach is the need to hold on to the SequenceNumber in order to retrieve the message later. If you happened to lose SequenceNumber, it is still possible to browse for deferred messages and retrieve those. More information here.
Scheduling a new future message
Another option would be to clone an incoming failing message, schedule it for some time in future using BrokeredMessage.ScheduledEnqueueTimeUTC and completing the original message. With this option, I'd recommend to send the new message scheduled in future to be dispatch using send-via feature, also known as Transaction Processing, to leverage atomic operation of completing the incoming message and sending the outgoing one. This way the code will not produce "ghost" message if completion fails. More information here.
Scheduling using client, not message
Another option is to schedule using a client and not BrokeredMessage using client.ScheduleMessageAsync(). It will return aSequenceNumber` you need to hold on to, but using this API a message can be cancelled at any point in time w/o waiting for the schedule time to arrive or receiving the message. More information here.
I was wondering if there is a way to nack a message without having it being marked as redelivered in Solace.
Situation: there's a guaranteed queue being serviced by multiple subscribers and we want another subscriber to process a particular message. Very much an edge case.
Does anyone have knowledge about this or tried this before?
There's no way to do this.
You should try to ensure that the message never gets delivered to the subscriber that will reject the message.
Your options are:
Design the topic space such that this particular message gets sent to a different topic/queue with the different consumer bound to it.
Apply selectors on the consumers on the queue so that only selected messages are delivered to each consumer.
Configure the queue to expire and send messages to the dead message queue after a certain number of re-deliveries. The other subscriber can get the message from the dead message queue.
So I'm trying to get MSMQ messages forwarded from one machine to another (which is dead easy - I was surprised), but one of the requirements from the ops side of the house is that we need to be able to see a log entry somewhere when the remote server decides not to accept a message. For example, if I try to send to a nonexistent queue, like so:
MessageQueue remoteQueue = new MessageQueue(#"FormatName:Direct=OS:machinename\private$\notarealqueue");
remoteQueue.Send("Test", MessageQueueTransactionType.Single);
The message goes into the local delivery queue, and appears to get sent across the network, but because the queue doesn't exist, the remote MSMQ manager discards the message. However, there's no entry in the Event Log that I can find about the message being dropped on the floor, and that makes people nervous. The Microsoft/Windows/MSMQ/EndToEnd log only seems to involve successful messages, which doesn't seem particularly useful. Is there a log I'm not seeing somewhere?
You can use MSMQ dead letter queues for that.
message.UseDeadLetterQueue = true;
With that enabled, if message can't be delivered it will be sent to one of two system dead letter queues - one for transactional and one for non transactional messages. You'll also find there the reason why message was not delivered, which was the original destination queue, full message body, label, etc.
You can use one of tools for managing queues to resend or recover these messages.
The event log is solely for the health state of MSMQ. What happens to a single message is trivial and not logged in the event log. Imagine what would happen if a million messages were discarded and had to be logged in the event log.
I'm sending a message to a private queue via c# :
MessageQueue msgQ = new MessageQueue(#".\private$\aaa");
msgQ.Formatter = new XmlMessageFormatter(new[] { typeof (String) });
msgQ.Send(msg);
It does work and I do see the message in the queue.
However, is there any way to get an ACK whether the message got to the queue with success ?
ps
BeginPeek and PeekCompleted is an event which is raised when a message becomes available in the queue or when the specified interval of time has expired. it is not helping me because I need to know if the message that I sent was received by msmq. BeginPeek will be raised also if someone else entered a message to the queue. and the last thing I want is to check via BeginPeek - from who this message comes from.
How can I do that?
ps2
Or maybe I don't have to worry since msgQ.Send(msg); will raise an exception if a message wasn't inserted....?
I think what you are trying to do should not be handled in code. When you send the message, it is placed in the outgoing queue. There are numerous reasons why it would not reach the destination, such as a network partition or the destination queue being full. But this should not matter to your application - as far as it is concerned, it sent the message, it committed transaction, it received no error. It is a responsibility of the underlying infrastructure to do the rest, and that infrastructure should be monitored to make sure there are no technical issues.
Now what should really be important to your application is the delivery guarantees. I assume from the scenario that you are describing that you need durable transactional queues to ensure that the message is not lost. More about the options available can be read here
Also, if you need some identifier to display to the user as a confirmation, a common practice is to generate it in the sending code and place it in the message itself. Then the handling code would use the id to do the required work.
Using transactional queues and having all your machines enroll in DTC transactions likely would provide what you're looking for. However, it's kinda a pain in the butt and DTC has side effects - like all transactions are enrolled together, including DB transactions.
Perhaps a better solution would to be use a framework like MassTransit or NServiceBus and do a request-response, allowing the reviecer to respond with actual confirmation message say not only "this has been delivered" but also "I acknowledge this" with timeout options.
As Oleksii have explained about reliable delivery.
However this can effect on performance.
What I can suggest is:
Why not create a MSMQ server on the machine that is sending MSG to other system.
What I am thinking is
Server 1 sends MSMSQ to Server 2
Server 2 receives adds to queue
Server 2 process queue/fire your code here to send a MSMQ msg to Server 1
Server 1 receives MSG (any successful msg with MSGId)
Do your further task
This approach can be an extra mile, but will keep your servers out of performance Lag.
I've got a server side protocol that controls a telephony system, I've already implemented a client library that communicates with it which is in production now, however there are some problems with the system I have at the moment, so I am considering re-writing it.
My client library is currently written in Java but I am thinking of re-writing it in both C# and Java to allow for different clients to have access to the same back end.
The messages start with a keyword have a number of bytes of meta data and then some data. The messages are always terminated by an end of message character.
Communication is duplex between the client and the server usually taking the form of a request from the Client which provokes several responses from the server, but can be notifications.
The messages are marked as being on of:
C: Command
P: Pending (server is still handling the request)
D: Data data as a response to
R: Response
B: Busy (Server is too busy to handle response at the moment)
N: Notification
My current architecture has each message being parsed and a thread spawned to handle it, however I'm finding that some of the Notifications are processed out of order which is causing me some trouble as they have to be handled in the same order they arrive.
The duplex messages tend to take the following message format:
Client -> Server: Command
Server -> Client: Pending (Optional)
Server -> Client: Data (optional)
Server -> Client: Response (2nd entry in message data denotes whether this is an error or not)
I've been using the protocol for over a year and I've never seen the a busy message but that doesn't mean they don't happen.
The server can also send notifications to the client, and there are a few Response messages that are auto triggered by events on the server so they are sent without a corresponding Command being issued.
Some Notification Messages will arrive as part of sequence of messages, which are related for example:
NotificationName M00001
NotificationName M00001
NotificationName M00000
The string M0000X means that either there is more data to come or that this is the end of the messages.
At present the tcp client is fairly dumb it just spawns a thread that notifies an event on a subscriber that the message has been received, the event is specific to the message keyword and the type of message (So data,Responses and Notifications are handled separately) this works fairly effectively for Data and response messages, but falls over with the notification messages as they seem to arrive in rapid sequence and a race condition sometimes seems to cause the Message end to be processed before the ones that have the data are processed, leading to lost message data.
Given this really badly written description of how the system works how would you go about writing the client side transport code?
The meta data does not have a message number, and I have not control over the underlying protocol as it's provided by a vendor.
The requirement that messages must be processed in the order in which they're received almost forces a producer/consumer design, where the listener gets requests from the client, parses them, and then places the parsed request into a queue. A separate thread (the consumer) takes each message from the queue in order, processes it, and sends a response to the client.
Alternately, the consumer could put the result into a queue so that another thread (perhaps the listener thread?) can send the result to the client. In that case you'd have two producer/consumer relationships:
Listener -> event queue -> processing thread -> output queue -> output thread
In .NET, this kind of thing is pretty easy to implement using BlockingCollection to handle the queues. I don't know if there is something similar in Java.
The possibility of a multi-message request complicates things a little bit, as it seems like the listener will have to buffer messages until the last part of the request comes in before placing the entire thing into the queue.
To me, the beauty of the producer/consumer design is that it forces a hard separation between different parts of the program, making each much easier to debug and minimizing the possibility of shared state causing problems. The only slightly complicated part here is that you'll have to include the connection (socket or whatever) as part of the message that gets shared in the queues so that the output thread knows where to send the response.
It's not clear to me if you have to process all messages in the order they're received or if you just need to process messages for any particular client in the proper order. For example, if you have:
Client 1 message A
Client 1 message B
Client 2 message A
Is it okay to process the first message from Client 2 before you process the second message from Client 1? If so, then you can increase throughput by using what is logically multiple queues--one per client. Your "consumer" then becomes multiple threads. You just have to make sure that only one message per client is being processed at any time.
I would have one thread per client which does the parsing and processing. That way the processing would be in the order it is sent/arrives.
As you have stated, the tasks cannot be perform in parallel safely. performing the parsing and processing in different threads is likely to add as much overhead as you might save.
If your processing is relatively simple and doesn't depend on external systems, a single thread should be able to handle 1K to 20K messages per second.
Is there any other issues you would want to fix?
I can recommend only for Java-based solution.
I would use some already mature transport framework. By "some" I mean the only one I have worked with until now -- Apache MINA. However, it works and it's very flexible.
Regarding processing messages out-of-order -- for messages which must be produced in the order they were received you could build queues and put such messages into queues.
To limit number of queues, you could instantiate, say, 4 queues, and route incoming message to particular queue depending on the last 2 bits (indeces 0-3) of the hash of the ordering part of the message (for example, on the client_id contained in the message).
If you have more concrete questions, I can update my answer appropriately.